Conventionally, a substrate processing apparatus has been known which performs various processings on a substrate (e.g., a silicon wafer or a compound semiconductor wafer) by using a processing fluid such as, for example, an alkaline processing liquid or an acid processing liquid (see, e.g., Japanese Patent Laid-Open Publication No. 2012-099582).
In the conventional technology, the substrate is accommodated in a chamber to be subject to various processings, and an exhaust pipe is connected to the chamber so as to exhaust the atmosphere of the chamber therethrough.
However, the exhaust flowing through the exhaust pipe may contain components of the processing fluid, and in this case, a product (e.g., a crystal) may be attached to the exhaust pipe thereby causing clogging of the exhaust pipe such as, for example, a reduction of a flow path cross-sectional area of the exhaust pipe. Thus, in the conventional technology, a cleaning processing is periodically performed to wash off the product by supplying a cleaning liquid into the exhaust pipe.